Without getting into some
really long answers detailing some lengthy discussions.......
I pretty much agree that the real issue of the 1n9" barrels is the issue of tooling. Freedom group guys party line was that most LE orgs still shoot the cheapest ammo (55gr) so hence the 1n9". Yeah okay, I said and he's right but what the orthodoxy of the 223 universe doesn't know is that 55gr bullets can be shot in some pretty good groups out to 300m especially in shorter <16" barrels. Done it, seen it, etc.
But it still comes back to to cheaper cost of producing the barrels.
I think the ACR cost will be okay in the long run considering the SCAR price and its lack of availability and , I was told, The HK M556A1 (semi 416) will be available in Feb-March also. Retail around $3000.
As for a crappy trigger pull,

the ACR FCG is a M-16 FCG......sooooo..... you can easily tune the hammer, trigger, disconnect just as with an AR-15 !!!!!!!!! ;D Outstanding! I'm ordering some David Tubb's Superior Shooting spring kits just for the new ACR's. In about 2 hours, you can have a perfect setup by tuning and polishing the sear surfaces without changing any sear geometry. To top it off ,I use Brownell's action lube plus grease. Gives about a 4 lb clean single stage break with no takeup or creep.
I don't see why you could not use other after market FCG's if you used the BM factory pins.
One of Magpul's Masada criteria has always been to use the M-16 FCG parts.
Magpul reps told me, and their 2010 catalog shows some of the parts they will sell this year.
Included are the folding/collapsible stock, fixed stock, PRS ACR stock, handguards, lowers with interchangable grips, etc. And most of all, I sure hope Magpul has a fix for the UNergonomic standard OEM selector lever. It's in a strange place. It reminds me of some of the early MP-5 selectors.
As for the barrels, BM told me they will offer many combos once the ACR gets launched.
1n7" twists, 10.5",14.5",16", 18" SPR with various AAC suppressor mounts. Looks like the Freedom Group is one big happy family.

BM reps told me that barrel assemblies will be in the $300-350 range, much less than a complete upper the swap out. To me , the only downside, is that those barrels will need to be rezeroed unlike swapping out uppers.
NFA SBR's should be coming out to individuals by summer.
My hope that one day somebody like noveske will make some precesion ACR barrel units.
I really want a set of those RemingtonMPD modular rails too. I like them better than the BM tri-rail.
After seeing the new Surefire lights at SHOT , I can't wait the hang one on the ACR. With the new lights, an ATPIAL , an AAC can and some NV you will have a real tool. It will weigh as much as an M-1 Garand but it will be a slick , very modern piece. Since we humans are bigger and stronger than 70 years ago, we can handle the weight, can't we boys ?????? I personally need the exercise! I bet I have seen at least a 100 posts on other forums from whiny little bitches complaing about the weight. " But my AR only weighs 6 lbs !!!!" Gee, sounds like some guys have never carried much less shot a scoped deer rifle !
The barrels ARE AR-15 barrels but the gas piston assembly, barrel extension and or barrel lock-up and lever must be added. They are not that big a deal to make but those components may be cost prohibitive for a custom barrel maker to get into the market at this stage.
Once again, my standard line,
this ACR thing is just beginning.
Take a deep breath, Be patient and the journey will be a lot more fun.
I remember how excited I was in my younger days when some lady made some Tiger Stripe cloth stock and handguard covers for M-16A1's. It was my first accessory for my AR and it was years before any other neat stuff came out. It will take years for the ACR market to mature and expand. The quicker ACR's sell, the more options we will have.
Jay